Method and means for stacking articles

ABSTRACT

A stacker of newspapers of similar articles including an input conveyor, the discharge end of which is movable up and down over a paper stacking platform. Sensor controlled systems maintain the end of the conveyor adjacent the top of the stack as the stack height is increased. The stack is removed from the stacking platform after a selected number of papers have been piled up to form the stack. While the stack is being removed, a catcher mounted at the end of the conveyor is moved into position to catch papers in a starter pile and to hold them in a position that causes the starter pile to remain clear of the stack being removed. Thereafter, the conveyor is lowered as the catcher is removed so that the pile of papers is deposited on the stacking platform. Then the conveyor end moves up as the stack height is increased and the cycle is repeated.

United States Patent [191 Wiseman [4 1 Sept. 30, 1975 [76] Inventor:Raymond L. Wiseman, 1550 S.

Macon St., Aurora, Colo. 80012 22 Filed: Aug. 21, 1973 211 Appl. No.:390,295

Related US. Application Data [63] Continuation-impart of Ser. No.197,744, Nov. 11,

1971, abandoned.

[52] US. Cl 271/189; 214/6 DK; 214/6 G; 214/6.5; 271/199; 271/201 [51]Int. Cl. 8651-! 29/34; B65H 29/50 [58] Field of Search 271/201, 200,199, 189, 271/218, 80; 214/6 DK, 6 G, 6.5

[56] References Cited UNITED STATES PATENTS 1,985,547 12/1934 Quick eta1. 271/80 X 2.852,990 9/1958 Roe 271/189 UX 3,297,318 1/1967 Knecht...271/201 3,321,202 5/1967 Martin 271/201 X 3,419,266 12/1968 Martin271/201 X l l l 1 l I L l l [I l ZZ i /z-- z l i I 347 3,477,323 11/1969Osborn 271/199 X Primary E.\'aminerEvon C. Blunk AssislantE.\aminerBruce H. Stoner, Jr.

Attorney, Agent, or FirmGrover A. Frater 5 7 1 ABSTRACT A stacker ofnewspapers of similar articles including an input conveyor, thedischarge end of which is movable up and down over a paper stackingplatform. Sensor controlled systems maintain the end of the conveyoradjacent the top of the stack as the stack height is increased. Thestack is removed from the stacking platform after a selected number ofpapers have been piled up to form the stack. While the stack is beingremoved, a catcher mounted at the end of the conveyor is moved intoposition to catch papers in a starter pile and to hold them in aposition that causes the starter pile to remain clear of the stack beingremoved. Thereafter, the conveyor is lowered as the catcher is removedso that the pile of papers is deposited on the stacking platform. Thenthe conveyor end moves up as the stack height is increased and the cycleis repeated.

16 Claims, 16 Drawing Figures US. Patent Sept. 30,1975 Sheet 2 of8 US.Patent Sept. 30,1975 Sheet 3 of8 3,908,985

US. ateant Sept. 30,1975 Sheet4 of8 3,908,985

743 TPAS HIHHHHUQV XXXXXXXXXXXXXXXXXXIX WA N" US. Patent Sept. 30,1975

Sheet 5 of 8 METHOD AND MEANS FOR STACKING ARTICLES This application isa continuation-in-part of Application Ser. No. 197,744, filed Nov. 11,1971 and now abandoned. It relates to improvements in article stackers,particularly stackers of magazines, books, newspapers and otherpublications.

It is an object of the invention to provide an improved article stackergenerally and to provide an'improved book, magazine, newspaper andpublication stacker in particular. It is an object to provide a stackerwhich can operate more reliably at higher speeds, over a wider range ofstack heights, over a wider range of paper thicknesses, and over a widerrange of spacing between papers at delivery. A further object is toachieve those advantages at minimum cost.

The stacking of newspapers is particularly difficult. The papers areconventionally delivered to a stacking station on a conveyor inoverlapping fashion such that each paper overlies the preceding one inpart. They are usually conveyed with the folded edge leading and, whilethe invention is not limited to that arrangement, folded edge firstdelivery to the stacker is preferred. In one example, the invention isembodied in a stacker that will accept newspapers comprising any numberof pages up to one hundred and twenty pages at a rate to eighty-twothousand papers per hour. The cycle time for forming and dischargingpaper stacks is as short as 0.85 seconds. Thus, for example, the deviceis capable of forming and discharging stacks twenty papers high of onehundred and twenty page papers at the rate of seventy stacks per minute.

A number of factors operate to preclude tying the stacks into bundles atthe stacking position. That means that it is stacks of loose papers thatare being delivered from the machine at the rate of seventy per minute.The task is complicated by the fact that the standard newspaper isfolded along two edges and not along the other two, so that the heightof the stack is not uniform over its upper surface. Thus, the center ofgravity of the stack shifts from issue to issue as the number of pagesin the paper is changed from day to day. The invention employs both anovel method and novel apparatus to attain its objects and moresuccessful stacking.

The method utilizes a novel series of substeps to accomplish stacking.It has the advantage that it is capable of being practiced by a numberof different machines. It is best practiced by machines of the kindherein described. While machines of that kind may be variously embodied,the particular embodiment selected for illustration in the drawing isnow preferred.

In the method, a number of articles, such for example as newspapers, arecaught on a pile where they lie one on top of the next on their broadsurfaces. Advantageously, the papers are held so that those broadsurfaces lie in a plane that is tilted toward the folded edge of thepapers. Thereafter, the pile of papers is dropped vertically downward toa lower plane that is similarly tilted in the sense that it is tilted inthe same direction although not necessarily at the same angle.Thereafter, an additional quantity of papers is permitted to be added tothat pile to form a stack of some given or selected size. After thestack has reached that size, subsequently arriving papers are caught atthe upper plane where the first pile was formed and a second pile isformed while the stack below is moved laterally to clear the spacebelow.

The preferred apparatus includes a stacking platform above which islocated a structure which serves both as the terminus of the paperdelivery conveyor and as the carrier for a catcher on which the initialpile of papers is formed. The structure is movable toward and away fromthe platform so that the conveyor and catcher can be moved toward andaway from the platform. After an initial pile is caught on the catcher,the catcher, and so the pile is moved downwardly toward the platform.Thereupon, the pile is dropped on the platform to continue the stack asthe catcher moves away. As additional papers are delivered to the stack,the structure carrying the terminus of the conveyor system movesupwardly so that the papers are delivered to the stack at a pointimmediately above the top paper of the stack. In preferred form, theplatform is tilted downwardly toward a stop. That arrangement insuresthat the papers of the stack are maintained by gravitational force inproper position relative to one another. When the stack has beencompletely formed, the platform moves to a horizontal position in anaction that tends to push the stack toward the stop in a way that forcesthe stack to be squared up at its front and rear edges except for aplanned stagger to be described below.

In the preferred form of the invention, the catcher drops its pile tothe platform such that the papers do not free fall. Instead, they engagethe platform prior to being released from the catcher; that actionprovides an extra measure of stability. Also, the preferred embodimentincludes a provision for relative motion between the discharge end ofthe conveyor and the catcher to the end that there is no free fall ofany paper in being transferred from the conveyor to the catcher. In theembodiment illustrated, this relative movement is arranged so that theangle at which papers are delivered to the pile and at which they cometo rest on the pile is substantially unchanged as the pile is formed.

The preferred embodiment employs a novel means for discharging the stackof papers from the stacking position. That .discharging means permitssuccessive stacks to be discharged either like direction or in oppositedirections. The discharge element is a push rod that engages one edge ofthe stack or the other and removes it by pushing against the stack. Thepush rod is variable in length. It is longer when stacks are tall andshorter when the stacks are short. In the preferred embodiment thelength of the push rod is determined by the position of the dischargeend of the conveyor at the time that the stack is to be removed becausethe position of the discharge end of the conveyor at stack removal is afunction of stack height.

In accordance with another feature of the invention the speed at whichthe discharge end of the conveyor is moved up is adjustable with therate at which stack height increases. Separation between the dischargeend of the conveyor and the top of the stack is sensed and the conveyoris moved upwardly at different speeds according to the degree ofseparation.

The invention includes other features and advantages which will beapparent in the description that follows. Not all of these features needbe incorporated in every embodiment to achieve the objects of theinvention; but the objects are achieved in greater degree as the numberof those features is increased.

In the drawings:

FIG. 1 is a cross-sectional view taken on line 1-1 of FIG. 2 of the sideof a newspaper stacker embodying the invention;

FIG. 2 is a view in elevation of the input end or front end of thestacker;

FIG. 3 is a view in rear elevation of the stacker of FIGS. 1 and 2except that one structural member has been broken partly away and thecontrol cabinet has been removed;

FIG. 4 is a view partially in cross-section and partly in elevation of afragment of the input conveyor mechanism;

FIG. 5 is a pictorial view of a fragment of the apparatus by whichcatcher movement is controlled;

FIG. 6 is a cross-sectional view of one end of the catcher mechanism;

FIG. 7 is a view partially in section and partially in elevation of afragment of the apparatus by which the conveyor is raised and lowered;

FIG. 8 is a sectional view looking down on the structure that drives thestack discharge push rod;

FIG. 9 is a view in side elevation of the input conveyor arm andmechanism that drives the catcher;

FIGS. 10, 11, 12A, 12B and 13 are schematic diagrams of the controllerby which operation of the stacker is controlled;

FIG. 14 is a graph that describes stacker operation with time; and

FIG. 15 is a schematic diagram of the mechanical and electrical systemthat comprises the stacker.

In FIG. 1 the stacker is shown in the condition in which a stack hasjust been completed. The catcher is in position to start a new stack andhas caught one paper 10. The newspapers to be stacked are delivered in astream by a stream diverter, not shown, at the upper left corner of thestacker. They are transferred to a short section of conveyor 11 that maybe seen at the upper portion of FIG. 1 toward the left. That conveyorconducts papers to the central region of the unit. The initial papers ofa stack are caught in a pile or starter stack on a starter or catcherapparatus visible at the upper portion of the drawing toward the right.The initial pile is formed at the upper center region and then isdropped to, or deposited at, a stacking position immediately below inthe mid-region of the apparatus. It is stacked on a platform, part 14 ofwhich is movable between a horizontal and a tilted position. That partof the platform is shown tilted in FIG. 1. The stack is formed on thatpart. Thereafter, the movable portion of the platform moves down levelwith the remainder whereupon a push rod 20, operated by mechanism in thelower part of the unit, pushes the stack toward the viewer or away fromhim in FIG. 1 to make room for the succeeding stack. The space in whichthe stack is formed, either on the catcher or the platform, is calledthe stacking location.

The stack of papers is shown just prior to being lowered with theplatform. While the stack is forming, the papers are held with theirupper broad surfaces tilted. By that means, gravity can be utilized tomaintain the papers in an orderly arrangement. They gravitate toward astop 12 which extends from the level of the platform to the upperregions of the unit. When the stack has been completed, the movableplatform section 14 will be made to swing counterclockwise about pivotaxis 16 until its upper surface is flush with the upper surface 17 ofthe stationary platform portion.

Movement of the movable platform section is controlled by a cam andtoggle actuator 18. As the movable platform 14 swings to the right, lessof its upper face will extend to the left of the stop 12. Frictionbetween theplatform and the papers of the stack insures that'the rightedge of the stack continues to bear against the stop 12 as the platformswings and the stack is lowered to the horizontal position. Theproportions of the movable and stationary portions of the platform, theradius of the arc of platform movement, and the position of stop 12 areadjusted so that the juncture of the movable and stationary parts of theplatform occur midway along the width of the stack. A gap is providedbetween the movable and stationary portions through which a pusher rodcan be moved. The lower portion of pusher rod 20 is mounted upon a pairof chains 22. The chains are mounted on sprockets carried by a shaft 24which is coupled to a stack discharge drive motor 26 through a gear box28 and one of two clutches 30 and 31. A chain 27 is reeved over thesprockets in a figure S arrangement sothat the pusher rod 20 may bedriven in opposite directions by selective engagement of clutches 30 and31.

To prevent free fall of the papers to the stack, a means is provided formaintaining the discharge end 13 of conveyor 11 in a positionimmediately above the top paper of the stack while the stack is beingformed. This is done in the invention by moving the conveyor endrelative to the platform, or by moving the platform relative to theconveyor end, or both. In this embodiment, the preferred embodiment, itis the conveyor end that is made movable toward the stacking platform.The conveyor 11 comprises a series of rollers that extend transverselyto the path of paper movement. These rollers are connected by endlessbelts. One set of rollers and belts is disposed below the stream andanother set of rollers and belts is disposed above the stream. Thepapers are compressed between them and forced to move along as therollers are made to turn. The rollers of the upper set are numbered 32,33 and 34. Belt 35 extends around rollers 32 and 33 and belt 36 extendsaround rollers 33 and 34. The rollers of the lower set are numbered 37and 38 and the belt that interconnects them is numbered 39. The rollersare driven by a drive motor 40. A chain connects the motor output shaftto a gear 42. That gear is fixed to a shaft 44. The shaft extendsthrough the plate 46 to other gears and chains, not shown, which areconnected to the rollers of the conveyor. The conveyor rollers areturned at constant speed whereby the papers to be stacked arrive at theend of the conveyor at uniform velocity. The number of them that arrivewithin a given time depends upon spacing between the papers. Examinationof the drawings will show that the belts are really a number of belts inparallel and the rollers are sectioned and the sections are slightlytilted but the description will neglect that in the interest of clarity.

The plate 46 is part of the means by which the conveyor is moved up anddown relative to the stacking platform. The plate is part of an L-shapedarm which is identified by the reference numeral 48. There are two sucharms. The other 49 is visible in FIG. 9. They have substantially thesame shape and they straddle the conveyor and catcher mechanisms. Theshafts of rollers 32, 33 and 37 are journaled in the two arms. Theshafts of rollers 34 and 38 are free to move relatively to the arm. Theshaft of roller 38 is carried by a pair of support arms, one of which isvisible in FIG. 1 where it is designated 50. The other is visible inFIG. 4 and is numbered 50a. They carry a structure at their right endsin which the shaft of roller 38 is journaled. At its left end thesupport arm 50 is fixed to a shaft 51 which is journaled in the arm 48.Thus, roller 38 may swing up and down relative to arm 48 about the pivotaxis formed by shaft 51. The roller 34 is free to move up anddownrelative to arm 48 and relative to roller 33. The shafts of rollers33 and 34 are journaled in the ends of a structure 337 which holds thetwo rollers. The shaft of roller 38 is not journaled in arm 48. Atension spring in FIG. 4, is connected between arm 48 and the shaft ofroller 38 such that the roller is urged upwardly against the belt,omitted from FIG. 4, which encompasses rollers 32 and 33.

A structure 54 serves to supply a bias which tends to urge rollers 34downwardly relative to roller 33 and arms 48 and 49. It also measuresand provides a signal indicative of the position of the roller 34relative to arms 48 and 49. Thus, the structure 54 is a detector whosefunction is to sense the degree in which the sensing roller 34 is pushedupwardly relative to arms 48 and 49 and the discharge end of theconveyor. It provides a signal which actuates a servo control by whichan arm lifting motor 58 is employed to lift and lower the right end ofarms 48 and 49. The motor acts through a toothed pulley 61 and aconnecting chain 62 'to lift the end of the arms 48 and 49. When themotor 58 is reversed and the chain is extended, gravity pulls the armsdown.

The structure 54 includes one part that is fixed to arms 48 and 49.Specifically it is fixed to the cross member 48a in FIG. 4. It has alower part that is movable relative to the upper part and is connectedby a link 339 to the arms or bracket 337 on which the axes of rollers 33and 34 are mounted. Thus the upper part of structure 54 is fixed to arms48 and 49 and the lower part of structure 54 is fixed to the arms 337. Abias spring inside the structure'54 biases the lower part of thestructure to extended position. The effect of that is to bias the member337 to clockwise rotation relative to the arms 48 and 49 when viewed inFIG. 1. There is a limit to the degree in which the two parts ofstructure 54 can separate and that serves to limit the degree ofcounterclockwise rotation of support member 337 and roller 34. In FIG. 1the member 337, sometimes called the sensing arm, is rotated almost toits clockwise limit.

Structure 54 houses a series of switches whose fixed contacts arecarried with the fixed part of the structure and whose movable parts areactuated by the movable, lower part of structure 54. As the sensing arm337 is moved counterclockwise against the bias of structure 54 and fourswitches in the structure are closed in sequence. Since the sensing armis pushed to counterclockwise displacement by contact with the uppersurface of a stack, whether the stack be formed on the sensing platform14 or on the catcher, the degree of counterclockwise rotation and of thesensing arm and switch closure is an indicator of the degree ofseparation of the upper surface of the stack and the discharge end ofthe conveyor. In this particular embodiment the discharge end of theconveyor is the point at which the articles emerge from between therollers 33 and 38. The switches within the structure 54 are shownschematically as a rotary switch 343 at lines 2-29, 2-30, and 2-31, ofFIG. 13.

Returning to FIG. 1, the sensing roller 34 rotates counterclockwise, (inFIG. 1.) It may comprise a spoked wheel as shown. In this case it isprovided with L-shaped projections that extent radially outward and arebent clockwise. When the apparatus is operating and a stack is forming,the arm 48 is lowered sufficiently to bring those projections intocontact with the upper paper of the stack. As they rotate, they wipeacross the upper face of the top surface of the up) er paper of thestack and aid in maintaining it in abutting contact with the stop 12.They serve also to catch the leading edge of papers as they arrive andto hold that leading edge slightly above the top paper of the stack in adegree sufficient to reduce friction between the arriving paper and theone below it as the arriving paper moves to the top position. The use ofthe spoked wheel provides a secondary effect that is advantageous insome applications. It results in the slight staggering of the foldededges of successive papers in the stack. That stagger aids greatly inreducing the difference in height between the forward folded edge andthe rearward cut edge of the stack.

As the stack height increases, the roller 34 must rise. When it does, itmoves upward relative to arms 48 and 49. That upward movement is sensedin the structure 54 whereupon the motor 58 is operated to raise the endof the arms. As the arms are raised, the bias developed in structure 54maintains the roller 34 in contact with the upper paper so that the arms48 and 49 move up relative to the roller. That condition is sensed instructure 54 by switch 343 which again affects the controller. Together,these elements serve as a means for positioning the arm so that thedischarge end of the conveyor is immediately adjacent the upper surfaceof the stack whereby papers are added to the stack with minimum freefall and without any free fall in the preferred embodiment. The biasdeveloped in structure 54 exerts downward pressure on the stack by wayof the roller 34 whereby the roller force is utilized to compress thestack.

The description of the apparatus to this point has neglected the factthat papers will continue to arrive at the stacker while the completedstack is being moved from stacking position. A means is incorporated inthe invention to catch the first papers to arrive after completion of astack and to hold them at a point above the stack. After the stack hasbeen removed, those papers are deposited in the stacking position andthe stack is completed as previously described. In this embodiment, thatmeans comprises a structure that is carried by the end of the arms 48and 49. It includes catcher tines that straddle the roller 34 and belt36. Those tines can be moved to a position just below roller 34 and tothe end of the conveyor 11 where they will catch papers as they arrive.When the stack below has been moved to one side and the movable portionof the platform has been returned to the tilted position in which it isshown in FIG. 1, then the catcher is moved out of the way and the paperson the catcher are dropped or deposited onto the platform. In thisembodiment, that dropping is accomplished without free fall. Some partof the upper and lower papers remains in contact with the elements ofthe stacker as they are deposited or stacked. More particularly the cutedge of the papers fall into contact with platform section 14 before thecatcher tines release the folded upper edge Thereafter the tines moveaway and the upper part of the papers fall the short distance to theplatform section. That method promotes gravitational action to urge thefolded edges against the stop.

To facilitate description, the collection of papers is called a stackwhen resting on the platform in the stacking position either tilted orflat. The collection of papers on the catcher is called a starter stackor pile. The pile is formed in the catching position and immediatelybelow the end of the conveyor whatever the position of arms 48 and 49may be. In FIG. 1, the catching mechanism is generally designated 66.This mechanism includes two sets of catching tines 68 and 70. The tinesare carred on bars or plates that extend between, and are pivotallyconnected to, a pair of yokes. The yokes are fixed to a shaft whichextends between arm 48 and its counterpart 49 on the other side of themechanism. Thus, the catcher drive shaft extends generally parallel tothe shafts of the conveyor rollers and indeed it is rotated by the motor40 through a drive mechanism best shown in FIG. 9.

The tines are connected to the drive shaft'but they have a pivotalmounting at a pivot axis removed from the axis of that shaft and theyare caused to pivot, as the shaft rotates, by a cam 72 which is fixed toarm 48. That structure is more clearly shown in FIG. and in FIG. 6.First, however, attention is invited to FIGS. 2 and 3, both of whichshow both of arms 48 and 49 straddling the conveyor and catchermechanism. Catcher 70 is shown to comprise three tines 70a, 70b and 70c.The catcher 68 also comprises three tines 68a, 68b, and 68c. Referringto FIG. 3, the roller 34 is seen to comprise two roller sections 34a and34b, both of which are provided with the L-shaped projections. The twoarms 48 and 49 straddle the stop 12. That stop is comprised of fourparallel sections 12a, 12b, 12c and 12d. The catcher tines and theroller 34 sections rotate in planes between the sections of the stop.The platform 14 is formed by the upper edge of four parallel plates 14a,l4b, 14c and 14d. Two of which, 14b and 14c, serve as the platform andtwo of which serve as supplements to stop 12.

Returning to FIGS. 5 and 6, the catcher tines are mounted upon twotraverse plates. The plate associated with the tines 70 is designated 80whereas the plate associated with tines 68 is numbered 82. The ends ofthese plates are pivotally connected to the pair of yokes, one at eachend of the plate. The yoke at the end toward arm 48 is designated 84,the other is designated 83. At their centers the yokes are mounted uponthe drive shaft 85. The yoke is fixed to the shaft and turns with it.The shaft is journaled in the arms 48 and 49 and it is rotated by achain driven gear 86. That gear is driven through a power train, shownin FIG. 9.'The power is derived from motor 40 and the speed of rotationis constant if not interrupted. The power train includes a clutch 87which is visible in FIGS. 2 and 9. It is called a stacker starter clutchand its electrical symbol appears in FIG. 12B at line 1-61.

The two plates 80 and 82 have pivotal connection to the two yokes 84 and83. That pivotal connection occurs at one edge of the plate. This may beseen in FIG. 6 where the plate 80 is pivotally connected to yoke 84 bythe pin 90. The plate 82 is shown to be connected to yoke 84 by thepivot pin 91. The other edge of the two plates are urged to rotationtoward the shaft 85 by a set of bias springs visible only in FIG. 6where they are numbered 92. They provide a bias which maintainsfollowers carried by the plates in engagement with cam 72. A follower iscarried by each of the plates and 82. In FIG. 5 the follower carried byplate 80 is visible and is designated 94. The plate itself is not shown.Both followers are shown in FIG. 6 in dotted lines. The followerassociated with plate 82 and the tine set 68 is designated 98.

The cam 72 comprises two parts; one of them is movable and is designated72a. That part can be retracted by a solenoid 100 to vary the timeduring a cycle when the tines are lowered from a position above theheight sensor roller 34 to the catching position immediately below thatroller.

In FIG. 1 the catcher tines 68 are positioned just below the roller 34.While the follower 94 is hidden in FIG. 1 comparison with FIGS. 5 and 6will make it apparent that the follower 94 has just passed that portionof the cam where the lower end of the plate 82 was permitted to swinginwardly in a counterclockwise direction whereby the tines 68 werelowered rapidly as an incident to that motion. In FIG. 6 the follower 98has moved up onto cam parts 72a almost to the tine dropping point. Thecam 72 is stationary and the shaft and yoke 84 are rotatingcounterclockwise. The follower 98 is being driven over the surface ofcam 72. If part 72a is retraced upwardly in FIG. 6, the follower willdrop suddenly to the edge surface of cam part 72 and tines 68 drop froma position above roller 34 to the position shown in FIG. 1. Thereafteras the catcher drive shaft 85 turns, the follower moves over the part ofthe cam surface which projects; downwardly and toward the left. Becauseof that shape, the catcher tines will move downwardly away from theroller 34b for some distance at substantially the same tilt angle thatthey are shown to have in FIG. 6. Thischaracteristic is incorporated sothat the paper pile on the catcher will lie at substantially the sameangle at which successive papers are arriving so that there is neitherinterference by the papers of the pile with the arrival of successivepapers nor free fall of the arriving paper to reach the pile.

While the pile is forming on the catcher, the stack below is pushed outof the way by pusher 20. Before the pile of papers on the catcher isreleased to the platform below, the movable portion 14 of the platformtilts upwardly and the arms with the conveyor and catcher mechanisms arepermitted to descend toward that platform. That action is completedprior to the time that the follower 98 reaches the lower part of thesurface of cam 72.'When the follower reaches that lower portion, tines68 rotate rapidly in a counterclockwise direction to release the pile ofpapers which drop to the movable part of the platform 14. In thepreferred embodiment shown, the catcher tines have dimensions inproportion to the axis of rotation of the catcher structure and thelength, of the upper surface of the movable platform so that the lowersurface of the pile of papers engages the left edge of the platformsection 14 prior to their being entirely freed from the catcher, so thatin this embodiment dropping means placing or depositing the pile on theplatform 14 with little or no free fall.

This action is graphed in FIG. 14. The left half of the graph depictssmall stack action; large stack action is shown at the right. The graphshows the distance above the horizontal platform section 17, with timeof: the left edge of platform section 14, the sensing roller 34 at theend of arms 48 and 49, and the end of the tines of catchers 68 and 70.In the graph, zero time has been selected to correspond to a time aftera stack has been formed and beginning at the time that it is to beremoved from the platform. At zero time the movable section 72a of thecam is retracted permitting the inward swing of the mechanism to whichtines 68 are attached. The tines rapidly fall below sensing roller 34and catch the next paper to arrive. Thereafter, the tines descend slowlyto greater distance below the roller as the pile is accumulated on thecatching tines 68. Immediately after the catcher tines fall below theroller 34, the platform 14 swings down level with the dischargeplatform. The pusher operates beginning at time zero to remove theprevious stack from the stacking position. At time 1 the edge ofplatform 14 begins to swing upwardly as the platform is moved to itstilted position. At the same time the follower 94 enters the lower curveof the cam and the tines move down more rapidly. The pile of papers onthe tines 68 extend leftward beyond the edge of the tines and arebrought into engagement with the upper edge of platform 14 about thetime that the arm is moved down to move the sensing roller to its lowestposition. The catcher tines are now being moved counterclockwiserapidly, out of the way and the pile is transferred from the catchertines to the platform. The sensing roller remains in engagement with theupper paper during that lowering operation. In fact, additional papersarrive during that period and are added to the pile. After the pile hasbeen transferred to the platform the sensing roller begins its upwardmovement. That begins at time 2. The separation between the sensingroller and the platform 14 at that time represents the height of thepile. That pile has become the bottom of the stack and as the stackincreases in height the roller 34 and the arm on which it is mountedmove upwardly.

There are two sets of tines and, while the stack is approachingcompleteness, the other set of tines 70 is approaching the positionwhere it will be controlled by the movable part of the cam. When thepaper counter indicates that the requisite number of papers have beenadded to the stack and that a new stack is to be started, the solenoid100 is actuated to remove the variable part of the cam and to drop thecatcher tine 70 below the sensing roller 34. The tines then begincatching successive papers and the platform 14 moves downward rapidlyunder the stop 12 pushing the stack of papers to vertical orientation.The stack is then pushed to the side.

The push rod and its actuating mechanism are shown from the side in FIG.1 and are shown from the front and rear in FIGS. 2 and 3. If one of theclutches is engaged, shafts 24 will rotate to carry the chains 22 aroundand the pusher 20 with them. Additional idler gears are included in thesystem and are mounted on a shaft 126. The path of movement of thecatcher extends completely around the stationary portion 17 of theplatform. While the top is not shown in the drawings, that stationaryportion is trapezoidally shaped in top plan view. The catcher movesthrough the space 132 at the right of section 17 (see FIG. 1). It cannotmove through space 132 until platform section 14 has been lowered. Thetwo clutches permit a change in rotational direction so that the catcher20 may be rotated completely around section 17 in the clockwisedirection or rotated completely around that section in thecounterclockwise direction or oscillated from the position shown to acorresponding position on the opposite side of the stationary platformsection 17. Thus, it can be moved transversely across the stackingposition so that it moves in the same direction as it traverses thestacking position on successive occasions, or it can be made to move inopposite direction on successive occasions. FIG. 8 is a view lookingdown on one of the chain and gear sets.

The upper part 20a of the pusher telescopes into the lower part 20b. Itis made to telescope in and out as the conveyor 11 is moved up and downwith arms 48 and 49. A connecting rod 341 is hinged at its lower end tothe top of section 20a. Theupper end of rod 341 has a sliding connectionon a tranverse rod 343 which extends between arms 48 and 49 below roller38 as best shown in FIG. 2.

One of the features of the scheme employed in the invention is that awide range of anomalies can be accommodated. The speed of rotation ofthe catcher mechanism shaft is fixed. Nonetheless, cycle time can bevaried somewhat because the time at which the catcher tines are loweredto catching position is controlled by actuation of clutch 87 and of thesolenoid 100. Up movement of the discharge end of the conveyor isdetermined as a function of stack height and down movement as a functionof stack height, push bar position, platform position and tine position.The formation of a stack continues until the count sensor mounted on thearms 48 and 49 has reached a preselected count. The sensor 150 appearsin FIG. 1. It is mounted on the arms 48 and 49 and moves up and downwith them. It counts individual papers and, at a selected count number,furnishes a signal to the control system. Then the pusher operates a camlinkage to move the platform down and to allow the platform to return toits up position by spring force. As the pusher moves it strikes limitswitches which control the synchronization of the catcher and inputconveyor motion.

When the push rod is rotated by claims 22, a cam roller 347 engages oneof the cam paddles 349. The paddle is fixed to the end of a lever whichis fixed of a shaft 351 to which an actuator bar 353 is also fixed. Theupper end of bar 353 has pivotal connection to platform 14. When theroller 347 pushes the paddle, the bar and platform move to the positionshown in dotted lines in FIG. 1. A second roller cam 357 bears against acam bar 359 which extends between the paddles whereby the platform 14 isheld in the dotted line position as the pusher bar moves through thespace 132. A bias spring connected to the paddles returns the platformto tilted position after the pusher has moved through space 132.

To this point the explanation of the movement of the arm catcher,platform, and the pusher has all but neglected the fact that means areincorporated in this embodiment for stopping rotation of the catchertines without stopping movement of the other elements. FIG. 9 shows theouter side of arm 49 together with the catcher drive. The catcherstructure is mounted on a shaft 85 and that shaft extends through thearm 49. The drive gear 86 is fixed to the shaft at a point adjacent tothe outer side of the arm. That gear is driven through a chain 158 by asmall gear mounted on a shaft 160. A larger gear 161 fixed to shaft isdriven by means of a chain 162 from the shaft 164 of roller 32. Theshaft 164 is ultimately driven by the motor 40 in the manner previouslydescribed. The shaft 164 is connected to chain 162 only when the clutch87 is energized. In this embodiment, the clutch 87 is energized anddeenergized by a logic system that includes switches that are carried bythe frame of the unit and are actuated by cams that are fixed to shaft172. That shaft is driven by gear 61 and its rotational position is anindicator of conveyor height.

There are four cams on shaft 172 and each of them cooperates with afollower that actuates a respectively associated one of four switches.The arrangement is best shown in FIG. 7. Cam 173 actuates switch MSLS.Cam 174 actuates switch TPLS. Cam 175 and cam 176 actuate switches TLSand BLS, respectively. BLS stands for bottom limit switch. The symbolTLS stands for top limit switch. TPLS stands for transfer position limitswitch. Finally, MSLS stand for maximum stack limit switch. In thisembodiment the arms 48 and 49 are lowered by gravity when rotation ofmotor 58 permits the shaft 172 to turn. Downward movement is opposed bythe action of a spring 361. The shaft 172 is rotated by the motorthrough a belt 363 and a drive gear 365. That gear is fixed to shaft 72as are the gears 61 and 367. Chain 62 extends from the gear 61 to arm 48and the chain 369 extends from gear 367 to arm 49. Spring 361 is fixedat one end to gear 367 and it is fixed at another end to a structure 371which is tied to the frame of the unit.

The system includes additional limit switches. One of them designated75LS, is mounted with solenoid 100 so that it is actuated when the stackstarter mechanism has a given degree of rotation. Other limit switchesare not shown in the structural drawings. While they form part of thesystem they are located ahead of the structure shown in the drawing. Oneof these switches is called 'SBLS which stands for bad stream and isactuated when the papers are arranged askew on the delivery conveyor.Another limit switch designated SPLS indicates that there is a stream ofpapers ready for delivery. Limit switche CJLS, senses any paper jam. isactuated by the paddle 373 and is housed in the unit 375 which can beseen at the top of FIG. 1. A limit switch structure CSLS can be seen inFIG. 1 where it is mounted on the arm 48 with solenoid 100. The symbolCSLS stands for cock sure limit switch." It is operated when the stackstarter is cocked and ready to intercept. Other limit switches aremounted in the lower part of the structure but are not visible. Theyinclude the platform limit switch, PLS, which senses position of theplatform, a discharge left limit switch, DLLS, which is operated by thedischarge mechanism to control interlocked positions and the stopposition and the direction of discharge. A corresponding discharge rightlimit switch RLLS performs the same functions when the stream isdischarged to the opposite side.

The structural relationship between these several limit switches and theremainder of the structure and their electrical relationship to thelogic controller and counter, and the electrical control in general, isdepicted in FIG. 15.

A schematic diagram of the control system is shown I in FIG. 15. Thatdiagram shows the primary elements of the mechanical system in schematicform. It shows the conveyor arm 48, mounted on the frame at pivot 44 andit shows the separately pivotally mounted sensing arm 337. It shows theplatform 14 and the pivot 16 by which that arm is pivotally mounted onthe frame. A stack of papers is shown mounted on the platform. The

pusher mechanism and pusher rod 20 shown and so is a stream diverter 392and a section of conveyor which are mounted ahead of the stacker unitbut which are included here because the stream diverter is controlled bysome of the sensing devices in the stacker and some sensing devices thatare associated with the conveyor section 390. The motor 40 operates thestacker conveyor system and also serves to rotate the catcher mechanism66 when the clutch 87 is engaged. The conveyor arm 48 and the sensingarm 337 pivot during operation so that the end of the sensing arm restson the top of the newspaper stack being formed. The conveyor arm 48 isheld down by gravitational force and it is lifted by the motor 58. It iscontrolled by a servo control unit 512 which controls the speed and thedirection of the motor. The servo control also includes a means by whichto dynamically brake the motor 58 to a stop. I

The platform 14 pivots during stacking operation and that pivotalmovement is powered by a platform moving system previously described andshown as boxes labled Pusher Motor, Clutch Left, Clutch Right and PusherMechanism.

Paper stacks are moved from the platform by the pusher mechanism andpusher 20. Power is supplied to the pusher mechanism by the pusher motor26. The pusher motor rotates continuously and the pusher mechanismmovement is controlled through a pair of clutches. One clutch 31 iseffective to move the pusher mechanism in one direction and the otherclutch 30 is effective to push it in the opposite direction.

The catcher mechanism 66 is powered by motor 40 through the clutch 78but it does not rotate unless the latch solenoid is operated.

The motors 26, 40 and 58, the stream diverter 392. clutches 87, 30 and31, and solenoid 100 and platform mover 312, are all energized from alogic controller and counter unit 520. Power can be applied to and beremoved from the system by manual operation of the logic control.Ordinarily, however, the power is applied manually and removedautomatically from the system by operation of the logic controller andcounter. That unit controls the sequence arid timing of the operation ofthe various elements in the stacker unit. A basic element in thatautomatic control is the counter switch 150. That switch is activated bythe individual papers of a stream of paper as they pass along the inputconveyor to be added to the stack. The counter switch simply provides asignal indicating how many papers have passed through the conveyor. Theoutput of that counter switch is applied by line 600 to the input of thelogic controller and counter. For convenience at this point input signallines to the logic controller are represented as being connected at aninput terminal 600. The output of the counter switch is applied to thatterminal 600. The counter (or logic controller) counts those signals andarranges to start a new stack and to discharge the previously formedstack when a predesignated count is reached.

Since the apparatus is to be capable of creating stacks of papers over awide range of paper thicknesses and delivery rates and a range of othervariables, means The time duration of the various events in the sequenceof stacker operation is quite variable whereby there is no singlecircumstance that is a reliable indicator that the system ismalfunctioning. In view of that, a number of sensors are provided (thelimit switches) which measure whether or not system operation does ordoes not fall within previously defined tolerance limits. Some of thoseswitches are position sensors that'cooperate with the logic controllerand counter unit to prevent the institution or termination of eventsuntil various pieces of apparatus have obtained a given position. Othersof those switches serve to shut down the stacker or divert the stream ofpapers from the stacker if the condition they sense persists for somepreestablished interval of time.

The limit switches were identified above and are shown in FIG. 15. Thefollowing is a list of the control components and their functions in theterminology of the art. The motor 58 is referred to as a servo motor.

CONTROL COMPONENTS STACK-PAK DB Discharge Brake Energizes to stopdischarge mechanism in rest" positions.

CRD Clutch Right Energizes to discharge stacks Discharge to right.

CLD Clutch Left Energizes to discharge to Discharge "left".

UPR Up Relay Energizes to control raising of Input Conveyor (directionand speed).

- Energizes to control lowering of Input Conveyor (direction and speed).

DNR Down Relay CO Counter Output ULR Up Limit Relay SDOR Stream DiverterOperating Relay SDV Stream Diverter Valve DRC Discharge Right ControlXRl Interlock Relay No. l

XR2 Interlock Relay No. 2

PR Platform Relay DSSU Down Stop/Start Up TOSR Top of Stack Relay UPC UpContactor DNC Down Contactor ASR Au tomatic Start Relay CONTROLCOMPONENTS-STACK-PAK-Cont.

CMR Cycle Monitor Relay 5 RDR Raise and Discharge Relay Energizes tosignal cycle monitor.

- Energized to select UP speed (POST DRIVE) of conveyor. Startsdischarge after intercept occurs.

- Energizes to insure that conveyor directions UP and not DOWN.

- Energized to stop UP (POST DRIVE) motion of Input Conveyor.

USR Up Stop Relay DSR Down Stop Relay SD2R Sequence 20 Down No. 2 RelayEnergized to signal that STACK STARTER has reached approximately 75% ofits rotational travel. (Where transfer starts.) SSR Stack Starter RelayEnergizes to engage STACK STARTER clutch. 25 ssc Stack Starter ClutchEnergizes to rotate STACK STARTER.

LR Latch Relay Energizes to energize Latch Solenoid.

LS Latch Solenoid Energizes to intercept first paper of the next stack.Energizes latch relay and clears counter.

30 CR Clear Relay relay in electronic counter to energize latch relay.

de-energizes to stop UP travel of conveyor.

energizes to divert stream by de-energizing SDV.

solenoid air valve energizes to divert stream. de-energizes to stopdischarge right"; or

to stop left" motion if selection is alternating".

energizes to interlock UP motion of conveyor with travel of dischargemechanism (via RDCR, USR, ULR).

energizes to interlock DOWN motion of conveyor with travel of dischargemechanism.

energizes when PLATFORM is down to prevent discharge mechanism fromstopping; and de-energizes to allow STACK STARTER to resume rotation anddischarge to stop.

to control clutch CRD,

brake DB.

XRl, XR2 and Cycle Monitor (CM) when discharging right.

to control clutch CLD, brake DB, XRI, XRZ and CM when dischargeingleft".

energized to start conveyor DOWN after transfer of new stack toPLATFORM.

relay energizes to stop down direction ,of conveyor and set updirection.

energizes to energize DSSU and set slowest up" speed. energized to setup direction for armature current.

energized to set downdirection for armature current. energizes to startthe stacker.

-Continued AOR Automatic Off Relay AOM Automatic Off Monitor USSD UpStop Start Down de-energizes to signal off" monitor AOD. energizes whenstream is not present to indicate machine is not in use.

energizes if entire cycle of discharging and starting a new stack takeslonger than preset time. turning off machine.

the portion preset. to turn off machinev energizes to establish thatstream diverter fully cycles anytime SDOR is energized energizes to stoppress and energizes if count sensor raises for a longer time thanactivate stop" signal or may be used to suit other customer interlocks.

energized to stop UP conveyor direction and start DOWN direction.

-Continued Loca- LocalTEM TlON FUNCTION TTEM TION FUNC'ITON M l-l 3Starts stacker and energizes controls. TOSSl l-78 Closes to set lowest(No. l) speed of M l-l2-3 Starts and stops motors (conveyor and SERVO.

discharge). TOSSl l-79 Opens to set lowest (No. l) speed of CR 2-l4External reset resets counter. SERVO. CR F43 Clo-565 energize CSLR andRDCR 1-56 Opens to re-activate TOSS when MCR l-] l Opens to preventpress stop on startdischarge bar reaches first interlock up of stacker.Closes to stop press (XRl and to allow second interlock stacker isturned off. (XR2) to function; to allow discharge AOR l-] l Closes whenstacker starts if stream b r t be stopped; all via RDR and is presentand stays closed as long RDRX. as stream is Present If Stacker is RDCRl-55 Closes to lock in RDCR until stack turned off, PCR energizes tostop t r i c cked. P XRl l-54 Closes to cancel post drive up-speed AOR2-l Allows ASR to energize if stream d perform XR] i l k fu ti ns.

approaches F TPR l-52 Closes to lock in TPR until locked. AOR-l -3010585 to Q and AORX a5 DSR l-53 Closes to mark transfer position longas Stream remains P when LC. is moving down and to prevent ASR l-l4Closes to energize controls and start DSR f Stopping fi l drive down fstacker as stream approaches. Opens SERVO Restarts 5 5 after Start- TPRl-SO Opens to prevent DSR from stopping PCR l-7 Closes to stop press. fil drive down f RV PC Opens to Signal press 9- SDZR l-47 Closes to lockinSD2R until s.s. CLSR l-l4 Closes to energize solenoid and interi k d,

' eP Stfeflm- 75LS l-48 Operated to rotate stack starter when CLSR-l1-7l Closes to energize solenoid and inter- 1 49 not k R l ed toindicate cept fl transfer position of stack starter. SSR l-6l Closes torotate stack starter. Sequence f r lease and o erated PR l-62 Closes toallow stack starter to resume to n; fi l d i d f SERVO.

rotation CSLS l-42 o e t d l h m k TPR l-62 Closes to allow stackstarter to resume 1 43 c zl gd ang rgagy t o int rc e gt sridmmnondischarge. DL-l l-63 Opens to release brake when dis- SO chargingleft. Closes to energize CO l-42 I Closes when count is reached to brakewhen discharging left. mtercept and dlscharge' DR-l l-63 Opens torelease brake when dis- CR l-43 Closes via MSLS and clear tointercharging right. Closes to energize cept, discharge and resetcounter. brake when discharging right. CSLR 144 C] t l l DR-l l-65Closes to discharge right. Opens to z g s and CLSR stop drive. DL-l l-67Closes to discharge left. Opens to USR Opens to p SERVO up t l and toStop driva prevent SERVO start up direction: and ULR l-74 Opens toprevent SERVO up direction. to prevent SERVO down stop ULR 1-75 Opens tostop SERVO up direction. (Prevents DS U from nergizing). USSD l-75 Opensto stop SERVO up direction TLS l-36 Same as USR above. USS Closes toSBLS l-34 De-operated to indicate bad-stream. DSSU l-74 Closes to startup irection. DSSU l-76 Opens to stop SERVO down direction. SDOR 35 opens"f FDR 1:17 Closes to start SERVO down after SDOR Opens to start Time?Open to transfer prevent flutter of stream diverter. DSR l-76 Op to pSERVO down before SDM l35 Opens to hold off sov to complete transfer.stream divert in case of momentary 25 2-7 Closes when SERVO motor isstopped. bad stream.

(Zero speed.) RDR l-73 Closes to set post drive speed of l 12 Opens toStop Stacks!" SERVO. CM O t d t' ate t -ofstack RDR 74 pens o 6 ac w opPR l-2l Closes to prevent stopping of -Continued Loca- ITEM TIONFUNCTION discharge while platform is down.

DRl 1-23-25 Selects DRLS or DLLS to act as DLl l-24-26 interlocks whenplatfonn is down and discharge stops when platform is up.

DR l-23 Prevents interlock No. l and PR from DL l-24 energizing ifplatform lowers before intercept of stream. (If PR is energized beforeDR or DL is energized, direction is unpredictable.

CLSR 1-25 Prevent interlock No. 2 from premature RDR-l operation ifplatform lowers before intercept.

XR2 1-32 Closes to "up stop and start down" of SERVO when previous stackis discharged.

DRC l-27 Opens to stop discharge when discharging right and right isselected.

DLC 1-31 Opens to stop discharge when discharging left and left isselected.

DLC 1-27 Opens to stop discharge when discharging right when alternateis selected.

DRC l-3l Opens to discharge when discharging left when alternate isselected.

DR 1-27 Lock-in when discharging right.

DL 1-31 Lock-in when discharging left.

SD2R l-37 If SERVO is stopped and not travelling SSR 1-38 up, and stackstarter has trans- FDR 1-38 ferred (SD2R and SSR contacts TOSSl 1-39closed), final down drive will start DSSU and lock-in FDR, TOSSl closesto down start, start up if I.C. comes down on started stack. DSSU locksin until up direction is made UPC.

If BLS is operated (bottom limit) or intercept takes place RDR-l closes,DSSU will energize until up direction is made.

Some troubles can be detected directly by a sensor. A paper jam is anexample. Other troubles cannot be detected directly. In that case theassumption is made that a trouble has occurred if the interval betweencertain related events exceeds some selected time. In that event thestacker is shut down or the cycle restarted or some other correctiveaction is taken. To that end the LOGIC CONTROLLER 520 includes timers,contacts or switches to control ignition and termination and resettingof the timers and solenoids whose energization and de-energization iscontrolled by the timers. These elements are shown in lines 2-6 through2-23 of FIG. 13. They are not essential to the invention and are notdescribed in detail. 7

Electrical power is supplied to the system by the lines at the upperleft in FIG. 10. The conveyor motor 40 and the discharge motor 26 areenergized when the contacts M at lines 1-1, 1-2 and 1-3 are closed.Power is applied to the remainder of the system through the transformerat lines 1-9 and 1-10.

Depressing start switch 501 at line 1-12 energizes relay M at that lineclosing the M contacts to apply power to motors 40 and 26. That makesthe input conveyor run. Other M contacts at lines 1-13 and 1-17 initiatethe diverter system to bring the paper stream to the stacker, thecounter will be reset and active and the machine will complete apartially completed cycle of operation to a condition in which thepusher bar has the position shown in FIG. 1 and the catcher tines are inposition just above the paper.

The latch solenoid CLS 100 is energized by relay CLSR, line 142, whichis energized through the counter relay contacts CO or the Clear Relaycontact CR and limit switch CSLS at that line. That causes the catchertines to move down into catching position. The

CR relay is operated by MSLS, the maximum stack height-limit switch orby pushing the manual clear button at line 1-46.

5 When the tines move to intercept position, the other part of CSLS atline 1-43 closes as shown to energize CMR at line 1-57, RDR and RDR-1 atlines 1-55 and l-56 start raising of the input conveyor and operation ofthe ejector bar. (See contacts at lines l-25, 1-29, 1-73, l-74, l-41 andnote that SSR is energized when intercept occurs because 75LS isclosed.) SSR is energized through 75LS at line-1-49 until 7 SLS opensafter the catcher tines have moved down to permit a starter pile toform. When 75LS opens at line 1-49 contact SSR at line 1-61 opens toopen the catcher drive clutch SSC. That stops the catcher but the pushrod continues. When the push rod clears the platform a limit switchenergizes PR at line 1-19 to reclose contact PR at l-62 to energize SSCthe stack starter clutch through TPR contacts which are closed if theconveyor height is not improper. That results in continuation of catchermovement through the point at which papers are transferred from thecatcher tines to platform A. The other section of 75 LS at line 1-48reenergized SSR so that catcher clutch SSC energization through SSRcontacts at line 1-61 is reestablished. Now FDR is energized. Itshold-in contacts are on line l-38. It has a contact at line 1-82 whichcloses to initiate energization of DNR and DNC to energize conveyordrive motor 58 in a direction to lower the conveyor.

The motor 58 and its controller are shown at line 1-84. It is aconventional DC. motor connected in a conventional speed control servo.The servo depicted in the drawings is produced by SECO, Inc. as itsmodel No. 8500.

Motor speed is controlled as a function of the voltage applied to theinput terminals of a trigger unit. The voltage level is adjusted bychanging taps on a voltage divider 505 at lines 1-87 through 1-94. TheTOSS switches are actuated to accomplish the tap changes. The RDR relaycloses to connect the trigger to another tap during up drive of theconveyor to increase the up speed just after intercept to remove theconveyor from the completed stack. That acceleration is referred to aspost drive.

Whether stack discharge is left or right is determined by operation ofthe manual switch at line 1-29 which disconnects one set of controls orthe other.

When the platform 14 is lowered by motion of push rod 20, PLS isoperated to energize PR at lines 1-18 and 1-19. While PR is energizedneither DRC or DLC can operate to halt push rod motion. The rod strikesDRLS and DLLS in that sequence if discharge is to the left andvice-versa. XRl and XR2 are energized is corresponding sequence by DRLSand DLLS.

Some of the protective arrangements are described as follows: XRl atline 1-23 energizes RDCR at line 1-54 which energized RDR and RDRX forthe duration of the catcher cycle to prevent conveyor motion in thewrong direction. RDRC also energizes USR to stop the conveyor if itrises above top limit as detected by TPLS.

XR2 at line 1-25 energized USSC at line 1-80 to stop conveyor up motionby deenergizing UPR and UPC and prepares for down motion by energizingDNR and DNC. When the platform 14 rises PLS opens to deenergize PR.Thereafter the discharge clutches may be opened by operation of DLLS andDLRS. SSC, starter clutch 78, may be energized after the conveyor islowered to the transfer position at which TPLS line 1-50 closes.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted exceptinsofar as is necessitated by the prior art.

I claim:

1. In a stacker of the kind that receives articles in a stream and formsthem into a series of stacks, in combination:

a frame;

a stacking platform carried by said frame at a stacking location;

an article conveyor pivotally mounted on said frame with its dischargeend positioned at said stacking location at a height variable withpivotal movement of said discharge end;

conveyor pivoting control means for maintaining said discharge end inclose proximity to the top of forming stacks of articles duringformation of the stack except at the time of initiation of a new stack;

said conveyor pivoting control means comprising a member carried by saiddischarge end and extending toward said platform and means sensitive tothe pressure applied to said member from the direction of said platformfor raising the platform in response to pressures greater than somegiven pressure and for lowering the platform in response to pressuresless than a given pressure.

2. The invention defined in claim 1 in which said conveyor pivotingcontrol means comprises holding means for holding the first article of astack at a height above said stacking platform for an interval of timewhereby said conveyor end will be positioned at an upward positionpermitting removal of a previously formed stack from said stackingplatform.

3. In a stacker of the kind that receives articles in a stream and formsthem into a series of stacks, in combination:

a frame;

a stacking platform carried by said frame at a stacking location;

an article conveyor pivotally mounted on said frame with its dischargeend positioned at said stacking location at a height variable withpivotal movement of said discharge end; conveyor pivoting control meansfor maintaining said discharge end in close proximity to the top offorming stacks of articles during formation of the stack except at thetime of initiation of a new stack;

said conveyor pivoting control means comprising holding means forholding the first article of a stack at a height above said stackingplatform for an interval of time whereby said conveyor end will bepositioned at an upward position permitting removal of a previouslyformed stack from said stacking platform;

said holding means comprising a catcher and means for moving the catcherto a position between said conveyor end and said stacking platform suchas to catch articles at a height sensed by said means for sensingheight.

4. The invention defined in claim 3 in which said catcher is carried bysaid conveyor for movement with said conveyor end as it pivots.

5. In a stacker of the kind that receives articles in a stream and formsthem into a series of stacks, in combination:

a frame;

a stacking platform carried by said frame at a stacking location;

an article conveyor pivotally mounted on said frame with its dischargeend positioned at said stacking location at a height variable withpivotal movement of said discharge end;

conveyor pivoting control means for maintaining said discharge end inclose proximity to the top of forming stacks of articles duringformation of the stack except at the time of initiation of a new stack;said conveyor pivoting control means comprising holding means forholding the first article of a stack at a height above said stackingplatform for an interval of time whereby said conveyor end will bepositioned at an upward position permitting removal of a previouslyformed stack from said stack-.

ing platform;

said holding means comprising a catcher and means for moving the catcherto a position between said conveyor end and said stacking platform suchas to catch articles at a height sensed by said means for sensingheight;

said holding means comprising a catcher in the form of tines carried bysaid conveyor and means for rotating said tines rapidly to a positionbelow said conveyor end to receive the next article discharged from theconveyor and then rotating said tines relatively slowly whereby topermit formation of a starter stack of subsequently arriving articlesand then rotating said tines rapidly to a position removed from saidstacking location; and

means for preventing movement of a starter stack from said stackinglocation as the tines are removed whereby the starter stack will bedeposited on said stacking platform 6. The invention defined in claim 5which further comprises means for removing stacks of articles from saidstacking platform during said interval of time.

7. The invention defined in claim 6 in which said stacking platform ismounted for pivitol movement about an axis transverse to the directionof movement to articles being discharged from said conveyor from a firstposition in which the first arriving part of an article to be stacked ispositioned below its last arriving part to a second, substantiallyhorizontal position; and means for maintaining said stacking platform insaid first position except during operation of said means for removingstacks.

8. The invention defined in claim 7 which further comprises means in theform of a stop for limiting motion of articles being discharged fromsaid conveyor such that they remain within said stacking location;

said stacking platform being pivotal about an axis extending on a lineabove the level of said stacking platform when horizontal whereby stacksof articles are forced against said stop as the platform is pivoted tohorizontal position.

9. In a stacker of the kind that receives articles in a stream and formsthem into a series of stacks, in combination:

a frame;

a stacking platform carried by said frame at a stacking location;

an article conveyor pivotally mounted on said frame with its dischargeend positioned at said stacking location at a height variable withpivotal movement of said discharge end; I

conveyor pivoting control means for maintaining said discharge end inclose proximity to the top of forming stacks of articles duringformation of the stack except at the time of initiation of a new stack;

said conveyor pivoting control means comprising holding means forholding the first article of a stack at a height above said stackingplatform for an interval of time whereby said conveyor end will bepositioned at an upward position permitting removal of a previouslyformed stack from said stacking platform;

means for removing stacks of articles from said stacking platform duringsaid interval of time;

said stacking platform being mounted for pivotal movement about an axistransverse to the direction of movement of articles being dischargedfrom said conveyor from a first position in which the first arrivingpart of an article to be stacked is positioned below its last arrivingpart to a second, substantially horizontal position;

means for maintaining said stacking platform in said first positionexcept during operation of said means for removing stacks;

means in the form of a stop for limiting motion of articles beingdischarged from said conveyor such that they remain within said stackinglocation;

said stacking platform being pivotal about an axis extending on a lineabove the level of said stacking platform when horizontal whereby stacksof articles are forced against said stop as the platform is pivoted tohorizontal position;

said means for removing articles comprising a push stack of articles;and

said push rod having adjustable height and means for adjusting itsheight to increase when said conveyor end is up and to decrease whensaid conveyor end is down.

10. A stacker of publications arid like articles, comprising incombination: 3

means in the form of a stacking platform disposed below a stackinglocation for holding stack;

means in the form of a catcher for holding a starting stack moveablefrom a first position over said stacking platform in said stackinglocation to a second position removed therefrom;

means in the form of a conveyor having a discharge end disposed at saidstacking location over said stacking platform and over said catcher,when said catcher is in said first position, for discharging articlesinto said stacking location onto said catcher when said catcher is insaid first position and onto said platform after the catcher is insecond position; 7

conveyor moving means for moving said discharge end of said conveyordownwardly when said discharge end is not located proximately to anarticle on either of said catcher and said stacking platform and formoving said discharge end of said conveyor up when it is locatedproximately to an article on either of said catcher and said stackingplatform; and

means for moving said catcher from said second position to said firstposition at a speed sufficient to catch the first article of a startingstack prior to its coming to rest on the top of a preceeding stack. 11.The invention defined in claim 10 in which said conveyor moving means iseffective to move the catcher with said conveyor end and comprisessensing means for sensing the separation between the discharge end ofthe conveyor and the top of a stack and for moving the conveyor end andthe catcher upwardly when the separation is less than a given degree.

12. In a stacker;

a platform at a stacking position;

conveying means for conveying articles to a catching position above theplatform;

catching means comprising a catcher for catching a pile of articles andholding them in the catching position and subsequently depositing thepile upon said platform;

means for selectively removing and replacing said catcher at saidcatching position;

a frame upon which said platform, said conveying means and said catcherand said means for selectively removing and replacing said catcher areall installed;

said conveyingg means and said catching means being mounted on saidframe for movement together vertically above said platform; and

means for lowering the catcher to successively lower planes relative tothe conveying means prior to dropping said pile on said platform.

13. The invention defined in claim 12 in which said means for loweringthe catcher comprises:

a first catcher drive element mounted on said means for lowering thecatcher for rotation about an axis normal to the plane of catchermovement, the catcher being mounted on said first catcher drive elementfor pivotal movement about an axis parallel to and spaced from saidfirst mentioned axis; and

means comprising a cam and cam follower connected one to the firstcatcher drive element and the other to said catcher for pivoting thecatcher about the second mentioned axis as an incident to rotation ofsaid first catcher drive element.

14. The invention defined in claim 12 in which said platform is movablerelative to the frame between a substantially horizontal position and aposition in which it is tilted downwardly in the direction towards whichthe discharge end of the conveyor is directed;

said invention further comprising a stop fixed to the frame andextending upwardly from a point adjacent the downward side of saidplatform; and

said invention further comprising means for moving the platform underthe stack to substantially horizontal position whereby the stack is madeto lie horizontally with the side arranged vertically.

15. The invention defined in claim 14 which further comprises:

discharging means for moving articles stacked on the platform instacking position from said position; and means for maintaining saidcatching means at catching position while the discharge means is movingarticles from below the catching position. 16. The method of stackingfolded papersarriving at a stacking position in a stream which includesthe step

1. In a stacker of the kind that receives articles in a stream and formsthem into a series of stacks, in combination: a frame; a stackingplatform carried by said frame at a stacking location; an articleconveyor pivotally mounted on said frame with its discharge endpositioned at said stacking location at a height variable with pivotalmovement of said discharge end; conveyor pivoting control means formaintaining said discharge end in close proximity to the top of formingstacks of articles during formation of the stack except at the time ofinitiation of a new stack; said conveyor pivoting control meanscomprising a member carried by said discharge end and extending towardsaid platform and means sensitive to the pressure applied to said memberfrom the direction of said platform for raising the platform in responseto pressures greater than some given pressure and for lowering theplatform in response to pressures less than a given pressure.
 2. Theinvention defined in claim 1 in which said conveyor pivoting controlmeans comprises holding means for holding the first article of a stackat a height above said stacking platform for an interval of time wherebysaid conveyor end will be positioned at an upward position permittingremoval of a previously formed stack from said stacking platform.
 3. Ina stacker of the kind that receives articles in a stream and forms theminto a series of stacks, in combination: a frame; a stacking platformcarried by said frame at a stacking location; an aRticle conveyorpivotally mounted on said frame with its discharge end positioned atsaid stacking location at a height variable with pivotal movement ofsaid discharge end; conveyor pivoting control means for maintaining saiddischarge end in close proximity to the top of forming stacks ofarticles during formation of the stack except at the time of initiationof a new stack; said conveyor pivoting control means comprising holdingmeans for holding the first article of a stack at a height above saidstacking platform for an interval of time whereby said conveyor end willbe positioned at an upward position permitting removal of a previouslyformed stack from said stacking platform; said holding means comprisinga catcher and means for moving the catcher to a position between saidconveyor end and said stacking platform such as to catch articles at aheight sensed by said means for sensing height.
 4. The invention definedin claim 3 in which said catcher is carried by said conveyor formovement with said conveyor end as it pivots.
 5. In a stacker of thekind that receives articles in a stream and forms them into a series ofstacks, in combination: a frame; a stacking platform carried by saidframe at a stacking location; an article conveyor pivotally mounted onsaid frame with its discharge end positioned at said stacking locationat a height variable with pivotal movement of said discharge end;conveyor pivoting control means for maintaining said discharge end inclose proximity to the top of forming stacks of articles duringformation of the stack except at the time of initiation of a new stack;said conveyor pivoting control means comprising holding means forholding the first article of a stack at a height above said stackingplatform for an interval of time whereby said conveyor end will bepositioned at an upward position permitting removal of a previouslyformed stack from said stacking platform; said holding means comprisinga catcher and means for moving the catcher to a position between saidconveyor end and said stacking platform such as to catch articles at aheight sensed by said means for sensing height; said holding meanscomprising a catcher in the form of tines carried by said conveyor andmeans for rotating said tines rapidly to a position below said conveyorend to receive the next article discharged from the conveyor and thenrotating said tines relatively slowly whereby to permit formation of astarter stack of subsequently arriving articles and then rotating saidtines rapidly to a position removed from said stacking location; andmeans for preventing movement of a starter stack from said stackinglocation as the tines are removed whereby the starter stack will bedeposited on said stacking platform.
 6. The invention defined in claim 5which further comprises means for removing stacks of articles from saidstacking platform during said interval of time.
 7. The invention definedin claim 6 in which said stacking platform is mounted for pivitolmovement about an axis transverse to the direction of movement toarticles being discharged from said conveyor from a first position inwhich the first arriving part of an article to be stacked is positionedbelow its last arriving part to a second, substantially horizontalposition; and means for maintaining said stacking platform in said firstposition except during operation of said means for removing stacks. 8.The invention defined in claim 7 which further comprises means in theform of a stop for limiting motion of articles being discharged fromsaid conveyor such that they remain within said stacking location; saidstacking platform being pivotal about an axis extending on a line abovethe level of said stacking platform when horizontal whereby stacks ofarticles are forced against said stop as the platform is pivoted tohorizontal position.
 9. In a stacker of the kind that receives articlesin a stream and forMs them into a series of stacks, in combination: aframe; a stacking platform carried by said frame at a stacking location;an article conveyor pivotally mounted on said frame with its dischargeend positioned at said stacking location at a height variable withpivotal movement of said discharge end; conveyor pivoting control meansfor maintaining said discharge end in close proximity to the top offorming stacks of articles during formation of the stack except at thetime of initiation of a new stack; said conveyor pivoting control meanscomprising holding means for holding the first article of a stack at aheight above said stacking platform for an interval of time whereby saidconveyor end will be positioned at an upward position permitting removalof a previously formed stack from said stacking platform; means forremoving stacks of articles from said stacking platform during saidinterval of time; said stacking platform being mounted for pivotalmovement about an axis transverse to the direction of movement ofarticles being discharged from said conveyor from a first position inwhich the first arriving part of an article to be stacked is positionedbelow its last arriving part to a second, substantially horizontalposition; means for maintaining said stacking platform in said firstposition except during operation of said means for removing stacks;means in the form of a stop for limiting motion of articles beingdischarged from said conveyor such that they remain within said stackinglocation; said stacking platform being pivotal about an axis extendingon a line above the level of said stacking platform when horizontalwhereby stacks of articles are forced against said stop as the platformis pivoted to horizontal position; said means for removing articlescomprising a push rod and means for driving the push rod against a stackof articles; and said push rod having adjustable height and means foradjusting its height to increase when said conveyor end is up and todecrease when said conveyor end is down.
 10. A stacker of publicationsand like articles, comprising in combination: means in the form of astacking platform disposed below a stacking location for holding stack;means in the form of a catcher for holding a starting stack moveablefrom a first position over said stacking platform in said stackinglocation to a second position removed therefrom; means in the form of aconveyor having a discharge end disposed at said stacking location oversaid stacking platform and over said catcher, when said catcher is insaid first position, for discharging articles into said stackinglocation onto said catcher when said catcher is in said first positionand onto said platform after the catcher is in second position; conveyormoving means for moving said discharge end of said conveyor downwardlywhen said discharge end is not located proximately to an article oneither of said catcher and said stacking platform and for moving saiddischarge end of said conveyor up when it is located proximately to anarticle on either of said catcher and said stacking platform; and meansfor moving said catcher from said second position to said first positionat a speed sufficient to catch the first article of a starting stackprior to its coming to rest on the top of a preceeding stack.
 11. Theinvention defined in claim 10 in which said conveyor moving means iseffective to move the catcher with said conveyor end and comprisessensing means for sensing the separation between the discharge end ofthe conveyor and the top of a stack and for moving the conveyor end andthe catcher upwardly when the separation is less than a given degree.12. In a stacker; a platform at a stacking position; conveying means forconveying articles to a catching position above the platform; catchingmeans comprising a catcher for catching a pile of articles and holdingthem in the catching positioN and subsequently depositing the pile uponsaid platform; means for selectively removing and replacing said catcherat said catching position; a frame upon which said platform, saidconveying means and said catcher and said means for selectively removingand replacing said catcher are all installed; said conveyingg means andsaid catching means being mounted on said frame for movement togethervertically above said platform; and means for lowering the catcher tosuccessively lower planes relative to the conveying means prior todropping said pile on said platform.
 13. The invention defined in claim12 in which said means for lowering the catcher comprises: a firstcatcher drive element mounted on said means for lowering the catcher forrotation about an axis normal to the plane of catcher movement, thecatcher being mounted on said first catcher drive element for pivotalmovement about an axis parallel to and spaced from said first mentionedaxis; and means comprising a cam and cam follower connected one to thefirst catcher drive element and the other to said catcher for pivotingthe catcher about the second mentioned axis as an incident to rotationof said first catcher drive element.
 14. The invention defined in claim12 in which said platform is movable relative to the frame between asubstantially horizontal position and a position in which it is tilteddownwardly in the direction towards which the discharge end of theconveyor is directed; said invention further comprising a stop fixed tothe frame and extending upwardly from a point adjacent the downward sideof said platform; and said invention further comprising means for movingthe platform under the stack to substantially horizontal positionwhereby the stack is made to lie horizontally with the side arrangedvertically.
 15. The invention defined in claim 14 which furthercomprises: discharging means for moving articles stacked on the platformin stacking position from said position; and means for maintaining saidcatching means at catching position while the discharge means is movingarticles from below the catching position.
 16. The method of stackingfolded papers arriving at a stacking position in a stream which includesthe step of catching a number of papers on a pile such that they lie oneatop the next on their broad surfaces in an upper plane which is tiltedtoward the folded edge; depositing the pile of papers verticallydownward to a similarly tilted lower plane; permitting an additionalquantity of papers to be added to the pile to form a stack of givensize; after the stack has reached said given size, catching subsequentlyarriving papers at said upper plane in a second pile while moving thestack laterally to clear the space below the pile; the stack beinglowered from the tilted plane to a substantially horizontal plane priorto being moved laterally; and the stack being formed such that the upperpapers of the stack are arranged such that the upper papers of the stackare arranged such that successively higher papers have their folded edgeextending partly over the folded edge of the paper below and such thatthe folded edges of lower papers lie one above the other whereby thefolded edge of the stack is concave when the stack is lowered from thetilted plane.